Electric timing relay



E. MESTITZ 2,484,] l 0 ELECTRIC TIMING RELAY Oct. 11, 1949.

Filed July 18, 1945 [rain Murat:

Patented Oct. 11, 1949 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to electric timing relays or switches of the type wherein a load circuit is established for a certain period of time by a mass of mercury or other conducting liquid which upon operation of the relay is moved by the pressure of another fluid, particularly a heated gas, e. g. hydrogen, to form a conductive path between two electrodes arranged in a hermetically sealed vessel and aims at providing such relays or switches which are efficient and adjustable and which are relatively easy to manufacture.

A relay or switch according to this invention comprises two communicating containers, e. g. glass bulbs, holding a conducting liquid, e. g. mercury, and an expansion fluid, e. g. hydrogen, a heating element in the upper portion and a current supply electrode in the lower portion of the first bulb, whilst a load electrode is arranged in the lower portion of the second bulb, the two bulbs being connected by a tube having at least at one point a relatively small cross section, an elevated neck or dam being provided at the joining point of the said tube with the said second or load electrode bulb so that a conductive path is formed between the two electrodes when the mercury is pressed by the heated gas from the first bulb through the connecting tube and over the neck or dam into the second bulb and is interrupted again when the gas in the first or supply electrode bulb cools down and the mercury recedes from the said elevated neck towards the first bulb.

Another object of the invention resides in an operating electrode connected to a switch or a number of switches controlling the heater circuit and arranged in an enlarged portion of the connecting tube near the point where it joins the load electrode bulb and in means for automatically by-passing such operating switch or switches after they have been closed for a short time, and for maintaining the circuit of the heating element closed for a longer period until it is automatically interrupted by the movement of the mercury due to the continued expansion of the expansion fluid.

More objects of the invention will be apparent from the following description referring to the drawings which illustrate diagrammatically and by way of example an embodiment of the invention.

Figure 1 shows a relay with its mercury contents in the rest position. Figure 2 shows part of the relay with the mercury in the working or on position and Figure 3 shows the position of the mercury which causes automatic interruption of the relay.

The vessel of the relay is preferably of glass and comprises two bulb-like compartments I, 2 tapering towards their lower cup-shaped ends I2, it which communicate with each other through a tube 8 whose cross section, at least at one point of the tube, is relatively small. An elevated neck or dam I is arranged at the joining point of the said tube 3 with the cup-shaped part I 4. A supply electrode I3 which is connected to a suitable source of D. C. or A. 0. current is arranged in the cup-like part I2 of the bulb I, and a load electrode I5 connected for instance to a row of lamps 2 I' or other load which is to be controlled is provided in the cup-like part I4 of bulb 2. An operating electrode It is arranged in an enlargement 6 between the narrow part of the connecting tube 8 and the neck 7.

Electrode I6 is connectible via a number of press button switches 22 in parallel arrangement, to one end I I of a heating element 9 situated in the upper part of the bulb I, the other end IE3 of the heating element 9 being connected to that pole of the current supply which is not connected to the supply electrode I3.

The ends of a tube 3 of larger cross section than the tube 8 are joined to the ends of the tube 8. The tube 3 has the shape of an inverted V, one of its legs opening into the joining point between the cup I2 and tube 8. The walls of the joining passage are so shaped that an elevated darn 4 is formed between the cup I2 and the connecting tube 8, whilst the highest point I8 of the opening between the bulb I and the tube 3 is lower than the level in bulb i of the mercury in its rest position and also lower than the highest point 5 of the V-shaped tube 3. The other leg of the tube 3 joins the enlargement 6.

An electrode I1 for by-passing the push buttons 22 is connected to the same end I I' of the heating element as the said push buttons 22 and is arranged in that leg of the tube 3 which is nearer the bulb I, the lowest point of the electrode I1 be ing somewhat higher than the joining point I8 between the tube 3 and the bulb I.

It will be seen that the period of connection depends on the quantity of mercury contained in the bulbs I, 2 and in the connections between them. In order to make this quantity of mercury variable and thereby the setting of the relay adjustable a mercury reservoir I9 preferably of tubular shape is joined to the top of bulb 2. The tube I9 can be calibrated in units of time, c. g. minutes. More mercury 23 in the operating bulbs I and 2 and therefore less mercury 23' in the reservoir I9 causes longer periods of connection.

The operation is as follows: Pressing one of the buttons 22 connects the heating element 9 to the current supply 2!] via the supply electrode l3 and operating electrode I6. The gas above the mercury level in bulb l is heated up, expands and pushes the mercury into a position shown in Figure 2. Thereby a conductive path is formed over the dam l and connects the load 2! via the load electrode 55 and supply electrode [3 to the supply source 28. Another conductive path is formed between the supply electrode l3 and bypass electrode ll so that the heating element 9 remains connected to the supply 20 via electrodes ll, 13 when the press button is released after its initiating operation. Therefore the gas in bulb l continues expanding until the mercury level is depressed below the joining point l8 between bulb l and tube 3, whereupon gas from bulb l entering tube 3, brings the mercury in both legs of tube 3 to the same level as in bulb l, as indicated with full lines in Figure 3. When this position is reached, the mercury does not contact the by-pass electrode ii, the heater circuit is interrupted and the gas in bulb l begins to cool down, and to contract. Thereby the mercury is slowly sucked back through the narrow tube 8 until the conductive path between the supply electrode l3 and load electrode 55 is interrupted by the mercury receding from the dam l. Eventually the mercury comes again to the position indicated in Figure 1.

As will be apparent, the reduced diameter of tube 8 aiiects the time factor of the relay. The narrower the passage through tube 8, the longer it takes to move mercury from one bulb to the other in response to a certain pressure and, hence, the longer is the time constant of the relay.

If a press button switch is not released when the position of the mercury indicated with full lines in Figure 3 is reached, the heating element is still connected via the press button, and the gas which is further expanded by heating presses the mercury level in cup l2 and tube 3 further down until the conducting path between the supply electrode !3 and both the operating electrode l6 and load electrode I is interrupted by the mercury falling below the level of the dam '2, as indicated With dotted lines in Figure 3. The gas in bulb i then cools down and the mercury level in bull; l rises over the dam 4. As long however as a connection via a press button 22 persists in this state of operation no continuous light can be obtained from the lamps which will flicker whilst the mercury repeatedly rises over and falls below the dam l. In this manner damage of the relay is avoided.

Modifications are possible without departure from this invention. Other suitable conducting liquids can be used instead of mercury and other suitable expansion fluids, especially gases or vapours, instead of hydrogen. The container can be of glass or other suitable insulating material. Whilst the shapes shown in the drawing have been found most suitable for carrying the invention into effect it will be understood that various parts of the vessel can be slightly different Whilst retaining their main operational shape as before described.

Having thus described by invention, what I claim as new and desire to secure by Letters Patent is:

1. In a timing device, in combination a sealed vessel shaped to form two communicating bulb elements each having an orifice in its lower section, a first communicating tube connecting said two bulbs through the respective orifices, said tube including a narrowed section controlling the time delay constant of the device, the lower outline portions of said orifices each forming a dam elevated relative to the bulb bottoms and the tube bottom, a second communicating tube forming approximately an inverted V and having a wider cross-section than the first tube, each leg of said V-shaped tube communicating respectively with first t be at a point thereof each point adjacent to one of the orifices, said first tube including in its bottom a cup shaped portion positioned between the orifice of one of the bulbs and the joining point of the respective leg of the second tube, an electric heater resistor disposed within the upper portion of the other bulb, a lead-in electrode extended into each bulb through the respective bottoms thereof, a lead-in electrode extended into said cup portion through the bottom thereof, a lead-in electrode extended into the leg of the second tube adjacent to the bulb havin he stor element therein, said latter electrode having its lower end at a level higher than the level of the uppermost outline portion of the oriof the bulb containing the resistor element, a uantity of a heat expandible gas and of an electrically con-ducting liquid contained in said sealed vessel, the quantities and distribution of said gas and liquid within the bulbs being so selected in relation to the total volume of the vessel that below a predetermined gas temperature the level of the liquid is below the elevated dam of the bulb adjacent to said cup portion, y separating th supply of liquid in the two b and the electrode end in said tube leg is above the said liquid level, and that at a gas temperature above said predetermined temperature in response to a heating of the gas by said resistor element, the liquid levels in the first tube a e. the said leg rise to cover the said dam and leg electrode end for establishing electric connections between the electrodes in the two bulb bottoms and said leg.

2. A timing device as described in claim 1, in combination with a current supply circuit and a load circuit, one terminal of the supply circuit being connected. with one of two terminals of the resistor eler. ent, the other supply terminal being connected with the electrode of the bulb containing he resistor element, one terminal of the load circuit being connected to the first mentioned ly terminal, the other load terminal being rec-ted with the electrode of the other bulb, an switch means of the bush button type having two terminal contacts, one switch terminal being connected with the electrode of said cup portion, the other switch terminal being connected with the second resistor terminal, said second resistor terminal being also connected with said leg electrode, whereby the heater resistor circuit is closed in response to a closing of said switch contacts.

ERVIN MESTITZ.

REFEBENQES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,67%,489 Vicker- June 19, 1928 2,124,626 Mishelevich July 26, 1938 FOREIGN PATENTS Number Country Date 519,150 Great Britain Mar. 18, 1940 

